Free Weight Loss Calculator

How Long Will It Take to Lose Weight?

Enter your current weight, goal weight, and daily calorie deficit to get a realistic timeline and weekly milestones for reaching your goal.

Calculate Timeline ↓

Enter your details

Don't know your TDEE? Calculate it first →

The science of weight loss timelines

1

7700 kcal = 1 kg of fat

One kilogram of body fat contains approximately 7700 kcal of stored energy. To lose 1 kg, you need to create a total calorie deficit of 7700 kcal.

2

Safe rate: 0.5–1% body weight/week

Research shows losing 0.5–1% of body weight per week minimises muscle loss. For an 80 kg person this is 0.4–0.8 kg per week — achievable with a 400–800 kcal daily deficit.

3

Real results vary

In the first 1–2 weeks, weight loss is often faster due to water weight reduction. After that, results settle to the expected rate. Expect some weeks with no change — this is normal.

Why this timeline is an estimate, not a guarantee

The 7700 kcal-per-kg rule is a useful planning tool, but real-world weight loss is rarely perfectly linear. As you lose weight, your TDEE decreases too (a lighter body burns fewer calories), which means the same calorie deficit produces a slightly smaller weekly loss over time unless you periodically recalculate your TDEE. This calculator assumes a fixed deficit throughout, so treat the timeline as a reasonable estimate that will need adjusting every few weeks based on actual progress.

Water retention, hormonal cycles, sodium intake, and how much glycogen is stored in your muscles all cause day-to-day and week-to-week scale fluctuations that have nothing to do with actual fat loss — this is why weekly averages, not single weigh-ins, are the more reliable way to track progress. If your TDEE estimate itself is off (which is common, since all formulas carry roughly 10% error), your actual timeline will differ from this projection — recalibrate using your real-world results after 2-3 weeks rather than trusting the initial number blindly.

Frequently asked questions about weight loss

This is called a plateau and is extremely common. As you lose weight your TDEE decreases, so a deficit that worked initially may no longer be a deficit at your new, lighter weight. Water retention (from stress, sodium, or hormonal cycles) can also mask real fat loss on the scale for days or weeks at a time. Recalculating your TDEE at your current weight is the usual fix.
No — very large deficits (1000+ kcal/day) increase the risk of muscle loss, nutrient deficiencies, fatigue, and a higher chance of eventually abandoning the plan due to how unsustainable it feels. Research consistently shows moderate deficits (500-750 kcal/day) produce better long-term results because they're easier to maintain and preserve more lean muscle mass.
Yes — as a rule of thumb, recalculate every 5-7 kg lost, or every 4-6 weeks, whichever comes first. Since TDEE is based partly on body weight, your maintenance calories genuinely drop as you get lighter, and failing to adjust is one of the most common reasons weight loss progress stalls despite apparently 'following the plan'.
Transition gradually to your new maintenance TDEE rather than immediately returning to old eating habits — a common mistake is stopping the deficit abruptly and reverting to pre-diet intake, which often leads to rapid regain. Slowly increasing calories back to maintenance over 2-4 weeks, while continuing to monitor weight trends, helps make the loss stick.

More calculators